Agency continues to investigate Josh Connole, who was released for lack of evidence. Earth Liberation Front claims responsibility for costly firebombings.

Undercover FBI agents arrived about midnight at a home on a tree-lined street in Pomona, and with guns drawn they ordered a 25-year-old antiwar activist to his knees.

Josh Connole was handcuffed and arrested on suspicion of vandalism and arson that had caused $3.5 million in damages at four San Gabriel Valley auto dealerships. The destruction was allegedly done in the name of the Earth Liberation Front, a radical environmental group that signs its acts of destruction with the letters ELF.

The Sept. 12 arrest of Connole appeared to be a significant break for the FBI, which has been investigating ELF attacks across the country for the last 11 years. The group has claimed responsibility for millions of dollars in damage, including the burning of a Colorado ski lodge, an apartment building under construction in San Diego and new homes in Arizona and Long Island, N.Y. The San Gabriel Valley attacks damaged about 135 SUVs.

But four days after his arrest, Connole was released for lack of evidence. New details about the joint local and federal investigation, which is being led by the FBI, show there has been scant evidence made public so far linking Connole with the crimes. Federal agents have sent a pair of Connole's pants to a lab in Quantico, Va., and are waiting to see whether paint stains match paint left at the crime scene.

Court records show that an unnamed informant pointed authorities toward Connole, who shares similar physical characteristics with a tall, dark-haired man seen on a security videotape recorded at one of the dealerships.

Connole's lawyer, William Paparian, has filed a complaint with the U.S. Department of Justice, alleging the FBI violated Connole's civil rights. Paparian compared Connole's arrest with the treatment of Richard Jewell, the security guard who was named a suspect but never charged in the 1996 bombing at the Summer Olympic games in Atlanta.

At the lawyer's request, five of Connole's friends have signed sworn statements that he was helping two new residents move from the evening of Aug. 21 until between 3 and 4:45 a.m. Aug. 22, the morning of the arson fires. Police reports said the dealerships were hit between 2 and 4:30 a.m.

Last month, a man claimed in e-mails and telephone calls to The Times that he participated in the attacks and that Connole was innocent. The man did not give his real name or say where he lived.

Authorities have yet to find the caller, or exonerate Connole.

"He is a person who was arrested based on a probable-cause suspicion," said Agent Matthew McLaughlin, spokesman for the FBI's Los Angeles division. "The United States attorney and the district attorney's office decided not to file charges at the time. But the investigation continues and we can't comment further other than to say we are making progress in the case."

Arcadia Police Officer Jonathan Hudson was on early morning patrol Aug. 22 when he received a radio call at 3 a.m.: Monrovia police were investigating three vehicle fires.

At 3:40 a.m., Hudson drove past the Rusnak Motors dealership and noticed that several SUVs had been sprayed with red and blue paint. Sgt. Ken Harper found a security guard sleeping in one of the new vehicles, the police report said.

By sunrise, authorities began to tally the damage that stretched across four San Gabriel Valley cities.

Eight SUVs were damaged at Rusnak Motors in Arcadia. Four vehicles parked at private homes were spray-painted in Monrovia. Another 51 SUVS -- mostly Mitsubishi Monteros and Lincoln Aviators -- were damaged at two dealerships in Duarte.

A storage building at the Clippinger Chevrolet dealership in West Covina was set on fire. At least 72 SUVS -- including 39 new Hummers -- were burned or spray-painted. The attackers painted ELF and left messages accusing SUVs of ruining the environment.

Three security cameras at the Duarte dealership captured images of three suspects. The first was a thin white male with brown hair. The second was a white male with brown hair. A third person could be seen, but the images were fuzzy.

Within 48 hours, the FBI turned their attention to a Craftsman bungalow in Pomona, the home of several environmentalists and antiwar activists, including Connole.

Connole, who is thin, white and has brown hair, matched the general appearance of one of the men on the videotape. An affidavit filed in the case stated that authorities used an informant to find Connole. Another affidavit with details about the informant and what he or she said remains under seal.

If authorities were looking for a suspect with an interest in the environment and an anti-establishment point of view, Connole fit the bill.A self-described computer nerd, Connole graduated from a computer trade school in Anaheim in 1997. Since then, he has worked running credit checks for Experian, did computer work for Perot Systems, delivered pizzas, bused tables at Polly's Pies and served as assistant manager for Earthbound Trading Co.